Method of Monitoring a Tandem Connection in a Mpls Telecommunication Network

1. A method of simultaneously monitoring, in a Multi-Protocol Label Switching network, both a label switched path and a tandem connection of said label switched path, said tandem connection being a section of said label switched path comprising a sequence of succeeding nodes, said tandem connection to be monitored having an input node and an output node, said method comprising the steps of: receiving a first Operation, Administration and Management, OAM, packet at the input node, said first OAM packet having a switching header and an OAM header; generating at the input node a second Operation, Administration and Management, OAM, packet having an OAM header; inserting a tandem connection header, different from the OAM header, in said first OAM packet after said switching header; sending towards said output node both said first OAM packet with the tandem connection header and said second OAM packet; at said output node, identifying said second OAM packet according to the absence of said tandem connection header, and extracting said second OAM packet from said label switched path for monitoring said tandem connection; and at said output node, identifying said first OAM packet according to the presence of said tandem connection header, removing said tandem connection header, and forwarding said first OAM packet along said label switched path for monitoring said label switched path.

2. The method according to claim 1 , wherein said step of inserting a tandem connection header in the first OAM packet comprises the step of writing a predefined value in a experimental use field of said tandem connection header.

3. The method according to claim 1 , wherein said step of inserting a tandem connection header in the first OAM packet comprises the step of writing a predefined value in a label field of said tandem connection header.

4. The method according to claim 1 , further comprising the step of identifying a second tandem connection containing said tandem connection to be monitored.

5. The method according to claim 4 , further comprising: receiving a further first OAM packet at the input node of said second tandem connection; generating a further second OAM packet at the input node of said second tandem connection; inserting a tandem connection header in said further first OAM packet; sending through the output node of said second tandem connection both said further first OAM packet and said further second OAM packet, and identifying, at the output node of said second tandem connection, said further second OAM packet according to the absence of said tandem connection header.

6. The method according to claim 5 , wherein the tandem connection header inserted in both said OAM packets is the same, and the same tandem connection header is to be inserted in any additional tandem connection to be monitored in the label switched path.